1. Field of the Invention
The present invention relates to a hybrid absorption chiller which uses an aqueous lithium bromide solution as an absorbent and uses water as a refrigerant, and more specifically, to a hybrid absorption chiller in which generators which respectively use high-temperature steam and medium-temperature water, generated in an industrial process (steel manufacturing process), as a heat source are installed to generate a refrigerant at the same time, so that the production of refrigerant is increased and waste heat is effectively utilized.
2. Description of the Related Art
In a general steel manufacturing process, waste heat such as high-temperature steam and medium-temperature water is inevitably generated. As a method in which such waste heat is recovered and reused, a double-effect absorption chiller can be applied.
Roughly describing a double-effect absorption chiller, the absorption chiller using an aqueous lithium bromide solution as working fluid composes the following cooling cycle. The absorption chiller generates a primary refrigerant in a process where the aqueous lithium bromide solution is phase-changed into steam by high-temperature steam within a high temperature generator, and generates a secondary refrigerant in a process where the steam is supplied to a low temperature generator and is heat-exchanged. The respective refrigerants generated in the high and low temperature generators are condensed by a condenser and are then supplied to an evaporator so as to be evaporated. Further, the refrigerant is supplied to an absorber and is absorbed by an absorbent to produce a weak solution. The weak solution is preheated through two heat exchangers, that is, a high-temperature solution heat exchanger and a low-temperature solution heat exchanger, and is then concentrated in the high and low temperature generators.
FIG. 1 is a conceptual view schematically showing the structure of the double-effect absorption chiller according to the related art. As shown in FIG. 1, a refrigerant pump 9 and solution pump 10 are driven in accordance with an operation signal, and a rated operation is carried out after 20 to 30 minutes of activating operation time.
At this time, a lower shell 11 connected to the refrigerant pump 9 through a pipe maintains high vacuum of about 6 mmHg.
In such a lower shell 11, the water as a refrigerant supplied through the pipe is sprayed over an evaporator 1 through a nozzle. Inside the evaporator 1, a first tube 12 as a cooling water pipe in which cooling water flows is installed. While being sprayed over the cooling water pipe, the refrigerant takes latent heat of vaporization on the cooling water pipe and is evaporated so as to be absorbed by an absorber 2 in a state of refrigerant steam. The cooling water cooled down by taking the heat of the cooling water pipe is used in another equipment in which cooling is required.
In the absorber 2, the strong aqueous lithium bromide solution as a absorbent absorbs the refrigerant steam evaporated in the evaporator 1 so as to become a weak solution of which the concentration is dilute. When the refrigerant steam is absorbed by the strong aqueous lithium bromide solution, heat is generated. The heat causes the absorbed refrigerant to be again separated into steam. Such reaction heat is removed by a second tube 13 installed in the absorber 2 in which cooling water flows.
While the weak solution, which has become dilute by absorbing water, is passed through a low temperature heat exchanger 6 and a high temperature heat exchanger 8 by the solution pump 10 installed in the lower portion of the absorber 2, the temperature of the weak solution increases. Further, the weak solution is supplied to the high temperature generator 5.
The weak solution is heated in the high temperature generator 5 by a heat source (not shown) so as to be divided into refrigerant steam and a concentrated lithium bromide solution. The refrigerant steam is sent to the inside of a third tube 15 of the low temperature generator 4.
The solution concentrated in the high temperature generator 5 is heat-exchanged in the high-temperature heat exchanger 8 and is then sent to the low temperature generator 4. Further, the concentrated solution is heated by the refrigerant steam passing through the third tube 15 connected to the high temperature generator 5.
While the refrigerant steam generated in the low temperature generator 4 and the refrigerant steam generated in the high temperature generator 5 pass through the third tube 15, the refrigerant which is heat-exchanged in the low temperature generator 4 is supplied to the condenser 3. The supplied refrigerant absorbs the reaction heat in the absorber 2 so as to decrease the temperature of the solution within the absorber, and is then cooled and condensed by the flowing cooling water so as to be supplied to the evaporator 1 in a liquefied state. Further, the concentrated solution is passed through the low temperature generator 6 and is absorbed while being sprayed over the absorber 2.
A controller (not shown) which is installed inside the high temperature generator 5 controls the solution pump 10 in accordance with the temperature level of the solution within the high temperature generator 5 so as to adjust an amount of solution which is sent to the high temperature generator 5. As such, the concentrated solution is supplied to the absorber 2 so as to again absorb the refrigerant steam, and such a process is repeated.
In the conventional absorption chiller having such a construction, however, a double-effect chiller using high-temperature steam as a heat source and a single-effect chiller using medium-temperature water as a heat source are independently developed and used. Therefore, a cost of developing a chiller is doubled, and the chiller equipments in industrial processes become complicated. Further, the respective chillers should be installed, resulting in an excessive equipment cost.